My first project was quite simple; I wanted to store information about a collection of mine in a database. But HTML couldnt interact with a database. So, I had two options; PHP (free) or ASP (licensed). Being that I had no income at the time (I was still in high school, and no job), the decision was easy.

You get to talk to real people who are happy you are helping themYou get feedbackYou are performing a serviceYou end up branching off in directions you could not have imagined on your ownYou are doing something good at the same time you are learningYou learn how non-technical people will actually use software, and discover how you have to make everything as simple as possible for them to control the content (hint: when they ask you for a manual or help files you know you did it wrong)

I personally started with a nice little survey type site that familiarized me with PHP and MySQL integration, then I moved on to a music site.Another type of site I might consider is URL shrinker, as that requires minimal PHP and MySQL knowledge (at least basic ones), yet create a nice, profitable little site.Good luck!